Human-robot cooperation with mechanical interaction based on rhythm entrainment-realization of cooperative rope turning

Adaptation of biological systems can be viewed as decreasing local interaction among subsystems to realize effective cooperation. Conversely, it is important for effective cooperation to evaluate and control local interaction. Based on this idea we present a method of realizing cooperative rope turning by a man and a manipulator. The rotating motion of the manipulator arm for rope turning can be specified by frequency and phase difference between the arm and the rope. The frequency is determined in real-time by rhythm entrainment using a phase-locked loop. The phase difference is related to the quantity of local inter-action, that is, energy transfer from the arm to the rope. Therefore it is controlled to realize desired energy transfer, which is estimated from human demonstration. In the experiment the manipulator can successfully adapt its motion to that of the human partner.